It is known to provide pile guides for underwater piling, see for example, IHC Sea Steel Limited's range of pile guides as described in WO99/11872 (Fast Frame pile guide), WO01/92645 (Finned Frame/follower pile guide) and WO03/074795 (Orientation Control pile guide). Another IHC Sea Steel Limited pile guide, as described in WO2009/024739, was specifically devised to allow for pile driving into an inclined substrate, such as the inclined side of a seabed canyon. The pile guide comprises a pile guide member which is pivotally mounted on a base frame to enable the pile guide member to pivot around an axis of rotation relative to the base frame. With such an arrangement, the orientation of the pile guide member may be adjusted to guide piles in a vertical orientation when the base frame rests on an inclined substrate with the axis of rotation horizontal (i.e. aligned transversely to the incline direction). However, such pile guides are not ideally suited for driving a pile into an uneven or undulating underwater substrate with localised variations in level. This is because such an underwater substrate will have a tendency to support the pile guide at different angles to the horizontal in different locations, which would result in piles being driven into the substrate in different, non-vertical orientations.
Yet another IHC Sea Steel Limited pile guide, as described in PCT/GB2011/050004, was devised to allow for pile driving into an uneven or undulating underwater substrate with localised variations in level. The pile guide comprises a pile guide member mounted on a base frame via a plurality of support members of variable length, with length adjustment of each of the plurality of support members determining the orientation of the pile guide member relative to the base frame. However, with such an arrangement, the variable-length support members must be strengthened or protected to withstand lateral loads experienced by the pile guide during use. The present invention has been devised with this issue in mind.